Reduced Growth Hormone Predicts Worsening Adipose Tissue Insulin Resistance in Adults with Obesity

OBJECTIVES: Adipose tissue distribution and glucose metabolism differ from adults with normal weight to adults with obesity. Growth hormone (GH) is closely related to obesity. Few studies have investigated the role of GH in adipose tissue insulin resistance (Adipo-IR). Herein, we investigated GH level and Adipo-IR in adults ranging from normal weight to obesity and the potential association between GH and Adipo-IR. METHODS: A total of 1,017 participants had their body mass index (BMI), GH, and Adipo-IR evaluated. Based on the BMI, participants were assigned to five groups from normal weight to class 3 obesity; based on the GH level tertiles, participants were divided into low-, medium-, and high-GH groups. RESULTS: In total, the GH level was negatively correlated with the BMI and Adipo-IR index (r = −0.32 and −0.22, respectively; both p < 0.001). The GH level gradually decreased, and Adipo-IR progressively increased from normal weight to class 3 obesity (all p < 0.001). Compared with the low-GH group, the reductions in the BMI, homeostasis model assessment of insulin resistance index, and homeostasis model assessment of β-cell function were more significant in both medium-GH and high-GH groups (all p < 0.05). Additionally, the Adipo-IR index in the high-GH group was significantly lower than that in the low-GH group (p < 0.001). For the multivariate regression analysis, serum GH concentration was an independent protective factor against Adipo-IR (β = −0.013, 95% CI: −0.025 to −0.001, p = 0.028). CONCLUSIONS: A marked suppression of GH level occurs in the adults with severe obesity. GH might be an important metabolic regulator associated with Adipo-IR.